In various semiconductor processes, activated ammonia radicals (NH*) are used for reaction chemistry. Certain classes of reactions require generation of ammonia radicals at low energy without creating hydrogen ions or radicals.
Many processes leverage plasma resources to generate ammonia radicals, with inductively coupled plasma (ICP) sources being the most common. ICP sources are physically large, complex, and expensive. These sources typically require dilution with a plasma feedgas that enables low pressure ionization and therefore operation, but competes with radical generation efficiency. Most importantly, however, substantial ion flux at relatively high ion energy is generated that is damaging to low-k dielectric substrates.
Further, ultraviolet (UV) sources typically consume large amounts of electrical power to do useful work. Much of this power is wasted in the parasitic production of ozone in the atmospheric air surrounding the UV source assemblies. The parasitic production of ozone is typically caused because dielectric windows used in ICP chambers are transparent to UV energy, which then gets absorbed by atmospheric oxygen and thus produces parasitic ozone. As such, the radical generation using ICP sources is not efficient.
It is in this context that embodiments arise.